Safety apparatus for mammoth tankers

ABSTRACT

A large tank has electrically conductive wires spaced laterally apart and extending from top to bottom as well as from side to side. They are electrically bonded to the tank for dissipating any static charges.

United States Patent Roberts [54] SAFETY APPARATUS FOR MAMMOTH TANKERS [151 3,681,657 [451 Aug. 1,1972

1,678,539 7/1928 Ticehurst ..l74/6X OTHER PUBLICATIONS Electrostatics in the Petroleum industry, edited by Klinkenberg et al.; Elsenvier Publishing Co. pp. 26- 27, 1958.

Primary Examiner-J. D. Miller Assistant Examiner-Harry E. Moose, Jr.

[52] 11.8. CI. ..317/2 D, 174/6, 317/2 R, Attorney-Thomas l-l. Whaley and Carl G. Ries 317/2 F [51] Int. Cl ..H05f 3/02 [57] ABSTRACT [58] Field of Search ..317/2 R; 174/6, 2 A large tank has electrically conductive wires spaced Cited laterally apart and extending from top to bottom as [56] References well as from side to side. They are electrically bonded UNITED STATES PATENTS to the tank for dissipating any static charges. 1,659,652 2/1928 Hall ..174/2 1 Claim, 2 Drawing Figures l j {7 M C 17 2 /2 I 47 j 3 l6 l7 2 [5 5 M) /5 /5 J SAFETY APPARATUS FOR MAMMOTH TANKERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to the field of large tankers. The problem arises with modern mammoth tank ships which have compartments large enough to create explosive conditions related to the cleaning of the tanks. In particular, the invention relates to the provision of means for dissipating static electricity charges.

2. Description of the Prior Art Heretofore, there have been various different solutions proposed in connection with the serious problem that has been found to accompany the use of mammoth tankers. The problem relates to the cleaning of the large tanks, which is done with high-pressure water jets. This has created conditions such that explosions have spontaneously taken place.

Some of the various solutions proposed have dealt with purging the tank compartment to remove any flammable gas. This was to be done in different ways, such as by filling the compartment with inert gas, or by filling the compartment completely with water to force out all gases. However, these prior solutions to the problem have been found impractible for various reasons, such as the expense and/or the .time required, etc.

SUMMARY OF THE INVENTION Briefly, the invention relates to a mammoth tanker which has a cargo compartment large enough to subject the vessel to damaging explosions upon cleaning said compartment with a high-velocity water jet. The invention concerns a combination which comprises a plurality of electrically conductive means crossing said compartment from one wall to another. The said conductive means is electrically bonded to said compartment walls and to said vessel.

Again, briefly, the invention concerns the combination with a mammoth tanker vessel which has at least one cargo compartment of a volume such that it is subject to damaging explosion occurrence upon cleaning with a high-velocity water jet. The combination includes a first plurality of thin electrically conductive barbed-wires spaced laterally apart and extending from the top to the bottom of said compartment. The said wires are electrically bonded to electrical ground of said vessel, and the combination includes a second plurality of thin electrically conductive barbed-wires spaced laterally apart and extending from one side to the opposite side of said compartment. The said lastnamed wires are electrically bonded to electrical ground of said vessel. The entire combination is arranged so that static electric charges will be safely dissipated.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and benefits of the invention will be more fully set forth below in connection with the best mode contemplated by the inventor of carrying out the invention, and in connection with which there are illustrations provided in the drawings, wherein:

FIG. 1 is a schematic cross-section view showing a compartment of a mammoth tanker, with static charge dissipation means according to the invention; and

' FIG. 2 is an illustration of a modified type of static charge grounding wire which may be employed in a system according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With the advent of the modern mammoth tankers, it has been found that the process of cleaning the tanks (which is necessary for handling of different cargos) has created dangerous conditions. Such conditions have led to explosions, resulting in serious and costly damage. While the causes of this difiiculty are not fully known, it appears that a condition is created which accompanies the use of high-velocity water jets in the cleaning process. Apparently, it builds static electrical charges of such magnitude as to cause spark discharge, which will, of course, ignite an explosive atmosphere.

This invention makes use of electrical conductors placed throughout the space within a compartment or tank. These are electrically connected to a good ground circuit for dissipating any static charges.

With reference to FIG. 1, there is shown a transverse cross-section of a vessel 11. It will be understood that this is schematic and represents one of the tanks or sections of the vessel. In this case it is of such a volume that it is subject to the occurrence of a damaging explosion.

Spaced laterally apart in the tank 11, there are a plurality of thin electrically conductive wires 12 that extend from atop wall 13 to a bottom wall 14 of the compartment or tank of vessel 11. These wires are. electrically bonded at the walls of the compartment 11, as in dicated by the welded or bonding joints 15 shown.

It will be appreciated that these wires 12 are electrically conductive material so that any static electricity charge that builds up within the tank 11 will be readily carried away via the electriccircuit including wires 12 and going to electrical ground of the vessel 11.

Similarly, there are a plurality of thin wires 16 that extend from side to side of the compartment in the vessel l I. These wires are electrically bonded by welds, or other electrically conductive joints 17 to the side walls. This is, of course, part of the electrical groundcircuit of the vessel 1 1.

It will be appreciated that these wires 16, as is the case with the vertical wires 12, are spaced laterally apart to form a grid which fills enough of the space within the compartment of vessel 11 to provide electrically conductive surfaces that will act as electrical conductors for draining away any static charge wherever it may build up within the vessel. The size of wires 12 and 16 may be relatively small so long as they have enough strength to withstand the amount of force that is created by the water jets during cleaning operations. It is contemplated that these wires might be a standard size, e.g., No. 8 AWG.

It will be appreciated also that the static charge dissipation may be enhanced by employing barbed wire such as a wire 21, illustrated in FIG. 2. This would have barbs 22 spaced along the length of the wire 21, and such barbed-wires 21 would be used in place of the conducting wires 12 and 16 that are illustrated in FIG. 1.

The structure of such barbed-wires 21 may, of course, take various different forms (not shown), such as wires with sharp points extending from the body of the wire. The FIG. 2 illustration is intended to indicate sharp-tipped barbs placed along the wire in the manner well-known with thetype of barbed wire employed in rural fences or in military operations. The purpose of such barbed-wire structure is that of providing sharppointed surfaces on the conducting wires in order to facilitate discharge of static electrical charges through the conductor.

While the foregoing description has been made in considerable detail, in accordance with the applicable statutes, this is not to be taken as in any way limiting the invention, but merely as being illustrative thereof.

I claim:

1. in combination with a mammoth tanker vessel having at least one cargo compartment of a volume such that it is subject to damaging explosion occurrence upon cleaning with a high-velocity water jet,

a first plurality of thin, electrically conductive barbed-wires spaced laterally apart and extending I from the top to the bottom of said compartment,

said wires being electrically bonded to electrical ground of said vessel,

a second plurality of thin, electrically conductive barbed-wires spaced laterally apart and extending from one side to the opposite side of said compartment,

said last-named wires being electrically bonded to electrical ground of said vessel,

all whereby static electric charges will be safely dissipated. 

1. In combination with a mammoth tanker vessel having at least one cargo compartment of a volume such that it is subject to damaging explosion occuRrence upon cleaning with a high-velocity water jet, a first plurality of thin, electrically conductive barbed-wires spaced laterally apart and extending from the top to the bottom of said compartment, said wires being electrically bonded to electrical ground of said vessel, a second plurality of thin, electrically conductive barbed-wires spaced laterally apart and extending from one side to the opposite side of said compartment, said last-named wires being electrically bonded to electrical ground of said vessel, all whereby static electric charges will be safely dissipated. 